Electron discharge device



March 23, 1937. SALZBERG 2,074,864

ELECTRON DISCHARGE DEVICE Filed May 29, 1956 INVENTOR BERNARD SALZBERG ATTORN EY Patented Mar. 23, 1937 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE Delaware Application May 29, 1936, Serial No. 82,453

4 Claims.

My invention relates to electron discharge tubes, more particularly to improvements in seals and the method of scaling in radial lead-in wires in the side walls of the envelope of the tube.

In one form of electron discharge device particularly useful at high frequencies and commonly referred to as the "acorn tube, the electrode mount assembly is provided with radial leadins. The mount is positioned within an envelope,

1o usually carbon coated on the inside and which prior to scaling comprises a pair of cup-shaped members each provided with an annular lip and between which lips the radial leads extend and are sealed. In assembling the tube the 15 mount is positioned to extend downwardly within one of the cup-shaped members so that the radial leads rest on the lip of the cup-shaped member. The other cup-shaped'member is then positioned over the leads so that the lips on the 20 cup-shaped members register with each other. Fires are then played on the lips until the glass flows around the leads to seal the lips. The lips may then be pressed together in a die, for example, to provide an outwardly extending an- 25 nular seal or press through which the radial leads extend. In some cases this method of sealing has introduced difflculties.

Due to the space which existed between the lips when the cup-shaped members and mount 30 were first assembled, the sealing fires would heat the parts of the mount within the cup-shaped members and cause oxidation of these members, resulting in gassy tubes and poor emission. If the mounts were not properly centered micro- 35 phonics would sometimes be introduced due to vibrations of mounts; Noise was sometimes caused by carbon particles which had been rubbed off the inside wall of the envelope when attempting to center the mounts.

40 The principal object of my invention is to provide an improved envelope construction for an electron discharge device and a method of sealing a mount having radial leads within the envelope of the tube.

45 The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in con- 50 nection with the accompanying drawing in which Figure 1 is an exploded view of an electron discharge device made according to my invention, Figure 2 is a finished perspective view of the completed tube shown in Figure l, and Figure 3 is a.

66 bottom view of Figure 2.

Referring to Figures 1 and 2, the envelope 9 of the tube encloses and supports a unitary electrode mount assembly comprising an indirectly heated cathode H) with the usual heater, a grid H, and an anode l2, which may be a box-like 5 structure made from sheet metal. The anode l2 has at each end extensions I3 which form shoulders for supporting electrode spacers I4 and [5 of insulation, such as mica, and preferably in the form of plates or discs transverse to the longitudinal axis of the tube. The extensions 13 are bent over against the mica plate members and may lie lie in slots in the edges of the plate members to rigidly secure the spacers to the anode so as to provide a rigid unitary electrode as- 15 sembly.

Radially positioned stifi conductors l6, which serve as lead-ins and also as mount support wires extend through an annular press H in the wall of the tube 9 and as best shown in Figure l have secured to their inner ends, preferably by welding, conductors 18 having one end threaded through the insulating disc or plate member M to secure the conductors IE to the plate members and the other end electrically connected to one of the electrodes mounted between the plates [4 and I5. The outer ends of conductor I6 serve as tube contacts to be received in a properly designed socket. This construction eliminates the need of the usual reentrant stem and press and materially reduces the overall dimensions of the tube.

While various methods may be used for assembling a tube of the type described, the usual procedure is after the electrodes have been assembled between the insulating mica discs [4 and I5 to provide a unitary mount structure, the combined lead-ins and tube contacts [6 are secured to the mica disc spacer Hi and connected to the electrodes by means of conductors 18 in the manner described above, one end of the conductor l8 being threaded through the mica disc M to secure conductors Hi to the mica and the other end of the conductor I8 being connected to an electrode. A getter tab l9 may be secured to the anode. This assembly is then positioned so that the mount extends downwardly within the cup-shaped portion 20 of the envelope 9 provided with annular lip 2|, the lead-in conductors resting on the lip.

A second cup-shaped portion 22 of the envelope 9 provided with an outwardly flared lip 23 is positioned over the leads so that the lips 2| and 23 register with each other. The outwardly flared lips facilitate assembly and sealing.

In accordance with my invention 1 provide the lips of the cup-shaped members with depressions and which in assembly register with each other and receive the radial leads i6 when the mount and envelope are assembled prior to sealing. After the mount and cup-shaped memhere have been assembled heating fires are played on the lips until the lips become plastic and flow around the leads. l The lips are then pressed together to insure proper sealing and to form the annular press ll through which the radial leads l6 extend. The tube is then exhausted through exhaust tube 26 and the envelope sealed off.

Because the leads and depressions on the lips of.the cup-shaped members can all register in only one position, the mount will always be properly centered and the possibility of contact between the carbon coating on the inside of the envelope and the mount during assembly is minimized, so that the chances of loose carbon particles and resulting noise is reduced to a minimum. Because the lips contact with each other when the mount and cupshaped members are assembled, the sealing fires do not reach within the envelope to oxidize the mount parts. This substantially eliminates gassy tubes due to oxidation. Because the mount is properly centered vibration is minimized and microphonics are substantially reduced. The time necessary for assembly is also materially reduced.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is 1. The method of assembling an electron discharge device having an envelope provided with an outwardly extending annular press, and a mount with radial leads extending through and sealed into said annular press, including the steps of forming a pair of cup-shaped members having annular lips, forming radially extending depressions in said lips, assembling the mount between the cup-shaped members with the depressions in registry and with the leads within said depressions whereby said mount and cupshaped members can be assembled in only one relationship, and sealing said lips together to form an annular press through which said leads extend.

2. The method of assembling an electron discharge device having an envelope of vitreous material provided with an outwardly extending annular press and a mount with radial leads extending through and sealed into said annular press, including the steps of forming a pair of cup-shaped members having outwardly flared annular lips forming radially extending depressions in said lips, assembling the mount between the cup-shaped members with the depressions in registry and with the leads within said depressions whereby said mount and cup-shaped memhere can be assembled in only one relationship, heating said lips to cause the vitreous material to flow around said leads and pressing said lips together to seal said lips together around the radially extending leads.

3. An envelope for an electron discharge device having a mount provided with radial leads, said envelope comprising a pair of cup-shaped members, outwardly flared annular lips on said cupshaped members, and radially positioned depressions in each of said lips to be positioned in registry-to receive the radial leads on said mount when the lips of said cup-shaped members are brought together for assembly.

4. An envelope for an electron discharge device having a mount provided with radial leads, said envelope comprising a pair of cup-shaped members, outwardly flared annular lips on said cupshaped members, and radially positioned depressions in each of said lips to be positioned in registry to receive radial leads on said mount when the lips of said cup-shaped members are brought together for assembly, and an exhaust tube extending from one of said cup-shaped members.

BERNARD SALZBERG. 

